* {
  margin: 0;
  padding: 0;
}

.footer {
  position: fixed;
  left: 0;
  bottom: 0;
  height: 50px;
  width: 100%;
  display: flex;
}

.footer .footer-item {
  flex-grow: 1;
  height: 50px;
  line-height: 50px;
  text-align: center;
  font-size: 14px;
}

.footer .footer-item.active {
  background-color: red;
}
